1. Field of the Invention
The present invention relates generally to wireless networking and more particularly to systems and methods for reducing power consumption in mobile communication devices having high power consuming network interfaces, such as WiFi (e.g., IEEE 802.11) or other heterogeneous radio technology interfaces.
2. General Background Discussion
Wireless Networks
Wireless networks can incorporate a variety of types of mobile devices, such as cellular and wireless telephones, laptop computers, wearable computers, cordless phones, pagers, headsets, and PDAs (Personal Digital Assistants). Such mobile devices may include network interfaces to enable fast wireless transmission and reception of voice and/or data over the wireless network. Typical mobile devices include some or all of the following components: a transceiver (i.e., a transmitter and a receiver, including single chip transceivers having integrated transmitters and receivers); an antenna; a processor; one or more audio transducers (for example, a speaker or a microphone); a data storage medium (such as ROM, RAM, EPROM, hard disk, etc); operational memory; a full chip set or integrated circuit; and interfaces (such as USB, CODEC, UART, PCM, etc.).
Wireless LANs (WLANs) may be employed for wireless communications wherein a user can connect to a local area network (LAN) through a wireless (e.g. radio frequency) connection. Wireless communications also can include signal propagation via light, infrared, and microwave transmission. There are a variety of WLAN standards that currently exist, such as, e.g., Bluetooth, IEEE 802.11, and HomeRF.
The IEEE standard known as 802.11 specifies technologies for wireless LANs and devices. Using 802.11, wireless networking may be accomplished with each single base station supporting several devices. Mobile devices may be pre-equipped with wireless hardware or a user may install a separate piece of hardware, such as a card, that may include an antenna. In addition, Multiple Interface Devices (MIDs) may be utilized in some wireless networks. MIDs may contain two or more independent network interfaces, such as a Bluetooth interface and an 802.11 interface, thus allowing the MID to participate on two separate networks as well as to interface with dedicated Bluetooth devices. The MID may have an IP address and a common IP (network) name associated with the IP address.
Wireless network devices may include Bluetooth devices, Multiple Interface Devices (MIDs), 802.11x devices (i.e., IEEE 802.11 devices including 802.11a, 802.11b and 802.11 g devices), HomeRF (Home Radio Frequency) devices, Wi-Fi (Wireless Fidelity) devices, GPRS (General Packet Radio Service) devices, 3G cellular devices, 2.5G cellular devices, GSM (Global System for Mobile Communications) devices, EDGE (Enhanced Data for CSM Evolution) devices, TDMA type (Time Division Multiple Access) devices, or CDMA type (Code Division Multiple Access) devices, including CDMA2000. Each network device may contain addresses of varying types including an IP address, a Bluetooth Device Address, a Bluetooth Common Name, a Bluetooth IP address, a Bluetooth IP Common Name, an 802.11 IP Address, an 802.11 IP common Name, or an IEEE MAC address.
Mobile Devices and Energy Consumption
Recently, mobile handheld devices with WiFi (IEEE 802.11) network interfaces have started to become popular. These devices include, for example, WiFi phones (also known as Voice over IP or VoIP), WiFi-cellular dual-mode phones and Personal Digital Assistants (PDAs). They allow users to take full advantage of heterogeneous radio technologies. WiFi, however, was not originally designed for energy-constrained (i.e., battery operated) handheld devices. As a result, the standby time of a handheld device with a WiFi interface is sharply lower than what is typically experienced with contemporary cellular mobile telephones. For example, a current typical WiFi phone may have a standby time of approximately 24 hours with 4 hours of talk time. On the other hand, a typical cellular telephone can have standby times up to 12 days with comparable talk times.
There are two basic categories of existing methods to make mobile devices with WiFi or other high energy-consuming network interfaces more energy-conservative. The first category modifies the WiFi and/or upper-layer protocols to make the protocols themselves more energy-conservative. These methods, however, require changes to widely accepted protocols and deployed products built to use such accepted protocols.
The second category does not change the networking protocols, but instead seeks to minimize the unnecessary consumption of energy by the high energy-consuming network interfaces. This category includes methods such as turning off power to the interfaces, or placing the interface in a low energy-consuming standby or “sleep” mode if possible, during time periods that the interface is not carrying user traffic. This can significantly reduce power consumption and hence increase the length of the mobile device's total standby time. The trade-off to such operation, however, is that during the time periods the interface is shut off, incoming user packets or voice call requests may arrive, and these packets will be lost.
To solve this problem, it has been proposed to implement a separate low-energy consuming receiver on the mobile device, in addition to other radio interfaces that already exist on the mobile device for supporting user applications, and to use it as an always-on signaling channel. When the mobile device is not actively in use, both the device and its high energy-consuming wireless network interface card are shut off. The low-energy consuming receiver will remain on to receive incoming communication signals and send “wake-up” messages to the mobile device upon receiving such incoming signals. Once awake, the mobile device uses its primary, higher power and higher rate channel to transport user traffic. This approach requires special hardware to implement the low energy-consuming signaling channel, which increases the complexity and cost of the mobile devices and also makes it difficult for widespread adoption because the necessary additional hardware cannot be easily implemented on existing mobile devices. It also has been proposed to turn off a network interface card after the interface remains idle for a certain predefined threshold. This method, however, fails to address the issue that incoming user packets and call requests may arrive during this time and become lost because the network interface is shut off.
Accordingly, there exists a need in the art for improvement in reducing energy consumption by handheld devices equipped with high energy consuming network interfaces, that increases the total standby time of such devices while minimizing the number of incoming data packets and call requests that may be lost while the network interface is turned off, and that does not require additional expensive hardware or modification of the basic network protocols themselves.